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Research
Projects Completed and In-Progress
ISNPS possesses a wide range of technical expertise, including: design, thermal-hydraulics and neutronics analysis of gas-cooled, liquid metal-cooled and heat pipe-cooled space nuclear reactors; design optimization and performance of heat pipe radiators; thermal management of Space Nuclear Reactor Power Systems (SNRPSs); transient modeling of heat pipes, including the startup from a frozen state; transient operation, safety and autonomous control of fully-integrated SNRPSs; modeling, design optimization and vacuum testing of high-temperature energy conversion devices, such as thermionic diodes, segmented and non-segmented thermoelectric devices, and Alkali-Metal Thermal-to-Electric Converters (AMTECs); and design, optimization, and thermal and stress analyses of segmented and cascaded thermoelectric converters for SNRPSs and Advanced Radioisotope Power Systems (ARPSs). The results of the research conducted at ISNPS since 1984 have been widely published in refereed technical Journals and Proceedings of technical conferences.
Some of the relevant technology and research projects conducted at ISNPS include:
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Design of gas-cooled, liquid metal-cooled and heat pipe-cooled space nuclear reactors; this effort at ISNPS has led to the development of three innovative reactor concepts: the gas-cooled pellet bed reactor (PeBR), the bimodal PeBR for nuclear electrical power and thermal propulsion applications, and the recent liquid metal-cooled, Sectored Compact Reactor (SCoRe) for the avoidance of single-point failure in the reactor cooling system.
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Neutronics design and analysis of SNRPSs; current efforts are investigating the use of Spectral Shift Absorber (SSA) materials, as a passive and effective means to ensure sub-criticality of fast-spectrum space reactors in the event of water/wet-sand submersion with or without core flooding subsequent to a launch abort accident.
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Nuclear fuel design, performance, and chemical and mechanical analyses.
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Thermal management of spacecraft, power systems, and thermal energy storage systems (e.g. employing the melting and freezing of LiF or other energy storage materials, with an understanding of the thermal and change-of-phase processes in microgravity).
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Interaction of lasers with spacecraft structure , and application of Monte Carlo uncertainty analysis for performance assessment and design of future space systems.
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State-of-the-art modeling and design optimization capabilities for heat pipe radiators which use alkali metal (cesium, rubidium, potassium, sodium and lithium) and low temperature (water) heat pipes, including the startup from a frozen state. These capabilities have been extensively verified using test data.
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Design, experimental development and testing of low-temperature heat pipes , such as water heat pipes.
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Modeling of transient and steady-state operations and safety of fully-integrated space nuclear power systems (e.g. the ISNPS models of the SP-100 space nuclear power systems for 100-1000 kWe power levels (SNPSAM) and of TOPAZ-II and other single-cell TFE type space nuclear power systems (TITAM), and the latest Dynamic Simulation Model (DynMo) for SNRPSs developed at ISNPS using the Simulink® platform integrated with Matlab®).
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Autonomous control of space power systems , with application to the SP-100 space nuclear power systems.
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Modeling, design optimization and testing of static energy conversion devices technology for space applications , including Thermionics (TI), segmented and cascaded ThermoElectrics (TE), and AMTEC converters.
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Experimental investigation and performance evaluation of Pluto-Express (PX) vapor-anode, multi-tube AMTEC cells , in collaboration with the AFRL in Albuquerque, Nichols Research, and AMPS. This effort resulted in major improvements in the design of PX-series AMTEC cells that were being tested jointly at AFRL. This testing, modeling and evaluation effort also included the development of thermal conductivity data for Min-K insulation materials and a comparison of its radial and lateral conductance with those of multi-foil insulation for PX cells.
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3-D transient and steady-state thermal and mechanical analyses of segmented and Skutterudite TE converters to assess the effect of adding different sublimation suppression coatings on the TE converters performance.
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Design and analysis of ARPSs with Cascaded and Segmented TE converters , with complete design and detailed analysis of the TE arrays and their thermal coupling to General Purpose Heat Source Bricks, and the electrical connections needed to achieve the desired load DC voltage.
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Submersion cooling experiments of high-performance computer chips using pool boiling of dielectric liquids such as HFE-7100 and FC-72 from micro-porous surfaces.
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Testing Facilities and Equipment
Experimental research being performed in the Thermal-hydraulics and Energy Conversion Laboratory (TECL) at the University of New Mexico’s Institute for Space and Nuclear Power Studies includes investigations of pool boiling and two-phase flow systems, thermosyphons and heat pipes, enhanced cooling of electronics, and performance tests of ThermoElectric (TE) unicouples, some of which continued for ~ 3700 hours. The TECL laboratory is equipped with a 200 kW DC power supply, two 1.0 kW DC power supplies, one 500 W DC power supply, three fully equipped data acquisition systems, each connected to a PC equipped with the most recent data analysis software (LabView), two chillers for a wide range of temperature control from –25 oC to 150 oC, and two vacuum test facilities.
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Vacuum Test Facilities and Denki v2.0 Software
The vacuum test facilities are designed for testing high-temperature devices up to 1300 K under high vacuum (~ 10 -8 Torr), or in inert gas such as argon or helium at < 1 atm. These facilities are fully instrumented for either manual or automatic, real-time data collection of voltage, current and temperature measurements during testing. Thermoelectric performance tests have been performed in both facilities in high vacuum and in argon gas environment at pressures between 0.6 and 0.75 atm.
Denki v2.0, a control and data acquisition software developed at UNM-ISNPS using the LABVIEW® platform, is capable of controlling heating, cooling and operation conditions of four different test devices simultaneously. The next version under development will be capable of simultaneously controlling up to 8 different devices under test in the four-bell jar vacuum facility. The software allows automatic control of the experiment to ensure preset operation and that safety margins are not exceeded. |
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 Denki can control tests in various ways. The heater power profile can be specified as a function of time, or a thermocouple reading can be set at specified temperature values. For example, the electrical power to the heater can be automatically adjusted to keep the hot side temperature of thermoelectric devices under test constant, while varying the load current during a current-voltage (I-V) sweep. The control software collects and saves data automatically during performance tests at specified intervals (seconds, hours or days). The cold junction temperature of the TE devices being tested is controlled using a refrigerating / heating bath circulator, with temperature control in the range of 25 oC to 150 oC. Higher cold side temperatures up to 400–500 oC are also possible.
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The first facility shown below is a general-purpose vacuum test stand designed to test large-scale assemblies or devices. This facility has a large glass bell jar, 18 inches in diameter and 30 inches high, and its own ion pump (230 l/s capacity down to 10 -8 Torr). This facility is equipped with a HP3497 multi-purpose data acquisition/ control unit for voltage and temperature measurements, a 4-channel Tektronic TDS420 digital oscilloscope for very fast transient measurements (~150 MHz), a CAMAC digital interface system, and other auxiliary digital multimeters. The data acquisition/ control unit, the digital oscilloscope and the CAMAC system are connected and controlled by a computer via GPIB (IEEE-488). |
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Our TECL engineers and researchers have accumulated a great deal of experience inperforming vacuum tests of TE and Thermionic (TI) converters at elevated temperatures up to 1800 K.
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 The second vacuum facility shown on this page is a four-bell jar system, for testing a number of devices simultaneously, but at four different conditions. The four glass bell jars are 10 inches in diameter and 12 inches high. This facility has its own vacuum ion pump (500 l/s capacity down to 10 -8 Torr). Each bell jar has its own angle valve to isolate it from the rest of the system, for operating at different conditions (hard vacuum or argon, environment, for example) for intermittent examination of test articles, or replacement with new articles while continuing the tests in the other three bell jars.
 The articles in each jar can be independently controlled using the existing HP3852A multi-purpose data acquisition / control unit for voltage and temperature measurements.
The fully assembled four-bell jar vacuum test facility is shown below. |
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Experimental Pool Boiling Facility
The experimental pool boiling facility at the Institute for Space and Nuclear Power Studies is dedicated to investigating immersion cooling with dielectric liquids on porous graphite and finned surfaces with the application toward electronics cooling applications. Systematic investigations are carried out using different boiling flat and finned surfaces (copper and porous graphite), at different liquid subcoolings (0 K ≤ Δ Tsub ≤ 30 K), and at different surface orientations (0° ≤ q ≤ 180°), using both FC-72 (C6F14) and HFE-7100 (C4F9OCH3) dielectric liquids.
A computerized system controls the experiments and records the boiling curves up to the critical heat flux. A high quality digital camera and a high quality digital video camera record the boiling at the surface in experiments as they run. This boiling visualization greatly aid the study of the hydrodynamics of the boiling process from the various surfaces used.
The pool boiling facility has two separate test stations capable of running experiments independently. Each station is fully equipped with its own test vessel, chiller, power supply, and computer controlled data acquisition system. The boiling surface and heater are mounted onto a Teflon block to ensure that all the power, generated by a 200 W power supply (Agilent E3634A), is dissipated through the boiling surface. The chiller (Thermo NESLAB RTE-7) is capable or removing up to 500 Watts of heat and together with the external water bath help to maintain the liquid bulk temperature to within ± 0.5K of the desired temperature. A control program developed using the LABView software runs the experiments as well as updates the boiling curve during the experiments and records the data onto the computer’s hard drive for further analysis.
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Computational Codes
- Reactor Design and Advanced Fuel Cycle
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MCNP5: Monte Carlo N-Particle version 5
MCNP5 is a general Monte Carlo radiation transport code capable of
transporting neutrons, photons, and electrons through virtually any materialin various geometries. A versatile program, MCNP is being used in modeling nuclear criticality and the design of space and terrestrial nuclear reactors and radiation shielding applications. ISNPS uses MCNP to analyze the criticality of its space reactor designs to determine that they meet operational and safety criticality requirements. It is also used for modeling shielding for neutrons and photons produced by reactors and radioactive sources.
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MCNPX: Monte Carlo N-Particle eXtended
MCNPX is and expanded version of MCNP capable of transporting nearly any particle at nearly all energy ranges. This allows the program to model high-energy physics applications such as solar radiation shielding for spacecraft and accelerator applications in addition to neutron and photon interactions. ISNPS is both a user of the current version of the code and a beta tester for new releases. Newer beta versions of MCNPX include a material isotopic depletion function, allowing for fuel burnup analysis to be performed internal to the program. ISNPS is currently evaluating MCNPX as a fuel-burnup analysis program for fast and thermal spectrum space and terrestrial reactors and for performing analysis of the production and burning of minor actinides, for the advanced fuel cycle and nuclear safeguard and nonproliferation applications.
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ORIGEN-ARP: Origen Automated Rapid Processing
Origen-ARP is an isotopic depletion and decay analysis program designed to characterize nuclear fuel assemblies. Part of the SCALE package, Origen-ARP provides for fast characterization of nuclear fuel under irradiation and decay conditions. ARP provides the Origen-S isotopic depletion code with problem dependent 3-group cross sections for its burnup calculations, allowing the package to model almost any commercial reactor currently in use. Origen-ARP is being used at ISNPS to study the behavior of MOX, (U,Th)O2, and inert matrix fuels for use next generation commercial nuclear reactors in reducing the production of minor actinide, reducing the mass and the volume of spent nuclear fuel.
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SCALE 5: Standardized Computer Analyses for Licensing Evaluation version 5
SCALE is a modular code that couples together functional modules, such as transport or depletion codes, allowing for combined analysis to be performed with a single code package. The program allows the user to use the same code package for handling neutronics, thermal, burnup, shielding, and other interrelated analysis in a coupled environment. SCALE 5 contains the 3D Monte Carlo transport codes KENOV and KENOVI, the burnup code Origen-S,
TRITON, which links the 2D discrete ordinates code NWET with Origen-S, among many others. ISNPS uses SCALE for studies involving commercial power reactors and advanced nuclear Fuel Cycle and fuel management applications.
- CFD Analysis and Simulation
- ANSYS
- COSMOS/FLOWORKS
- MATLAB/SIMULINK
- FENLAB
- SOLIDWORKS
- System Simulation & Transient Analysis
- HPTAM
- APEAM
- DynMo - TE
- DynMo - CBC
Recent Publications
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